TRANS-SYNAPTIC SIGNALING DURING NEUROMUSCULAR DEVELOPMENT

描述（由申请人提供）：尽管NF- kb已经在免疫、炎症和癌症的背景下得到了深入的研究，但对NF-？B在神经系统。在中枢神经系统中，NF-kB信号系统与神经退行性疾病、癫痫和神经元可塑性有关。在神经肌肉连接处，NF-kB的激活与与神经退行性疾病（营养不良和恶病质）和去神经支配相关的肌肉萎缩机制有关。尽管有这些观察结果，激活神经系统内NF-kB信号的细胞和分子机制仍有待明确定义。我们最近证实，NF-kB /Dorsal、IkB/Cactus和IRAK/Pelle激酶在突触后肌肉中发挥作用，控制果蝇NMJ的谷氨酸受体密度，这一过程与NF-kB在脊椎动物NMJ中的功能有关（Heckscher和Davis，回顾）。我们现在有初步的数据确定了一个跨突触信号系统，可以控制NMJ的NF-kB。在正向遗传筛选中，我们发现了分泌配体（TNFa）及其突触后受体（TNFR2）的突变，这些突变会损害果蝇NMJ的GluR丰度。我们提供的初步数据表明，tnf - α基因在位于NMJ附近的外周胶质细胞中表达，并且这种tnf - α来源对于控制GluR水平是必要和充分的。此外，已经确定TNFR2受体在果蝇肌肉中表达。因此，我们假设TNF-a和TNFR2基因在NMJ中定义了一个新的神经胶质到肌肉的跨突触信号系统。重要的是，已经证明TNFR2受体可以激活其他果蝇组织中的下游NFkB信号。因此，我们假设存在一个保守的，神经胶质到肌肉的信号系统，在胚胎后发育过程中控制谷氨酸水平和神经肌肉功能。我们提出实验来定义和阐述果蝇NMJ的这一信号系统。鉴于这些信号分子具有高度的进化保守性，我们预测我们的数据将与哺乳动物神经疾病和损伤期间NF-kB的功能直接相关。公共卫生相关性：在神经系统中，NF-kB信号系统与神经退行性疾病、癫痫和神经元损伤反应的机制有关。尽管这种进化上保守的信号系统很重要，但人们对NF- kB如何参与这些不同的过程知之甚少。我们提出的实验不仅将定义NF-kB如何在神经系统中被激活，而且还将定义NF-kB信号的输出，这可能与NF-kB在损伤和疾病中的作用直接相关。

DESCRIPTION (provided by applicant): Although NF-kB has been studied intensively in the context of immunity, inflammation and cancer, far less is understood about the function of NF-?B in the nervous system. In the central nervous system, NF-kB signaling system has been implicated in neurodegenerative disease, epilepsy, and neuronal plasticity. At the neuromuscular junction, activation of NF-kB has been implicated in the mechanisms of muscle wasting associated with neurodegenerative disease (dystrophies and cachexia) and denervation. Despite these observations, the cellular and molecular mechanisms that activate NF-kB signaling within the nervous system remains to be clearly defined. We recently demonstrated that NF- kB/Dorsal, IkB/Cactus and IRAK/Pelle kinase function within postsynaptic muscle to control glutamate receptor density at the Drosophila NMJ, a process relevant to the function of NF-kB at the vertebrate NMJ (Heckscher and Davis, in review). We now have preliminary data identifying a trans-synaptic signaling system that could control NF-kB at the NMJ. In a forward genetic screen we identified mutations in a secreted ligand (TNFa) and its postsynaptic receptor (TNFR2) that impair GluR abundance at the Drosophila NMJ. We present preliminary data that the TNF-alpha gene is expressed in peripheral glia that reside near the NMJ, and that this source of TNF-alpha is necessary and sufficient to control GluR levels. In addition, it has been established that the TNFR2 receptor is expressed in Drosophila muscle. Thus, we hypothesize that the TNF-a and TNFR2 genes define a new, glia-to-muscle, trans-synaptic signaling system at the NMJ. Importantly, it has been demonstrated that the TNFR2 receptor can activate downstream NFkB signaling in other Drosophila tissues. Therefore, we hypothesize the existence of a conserved, glial-to-muscle signaling system that controls GluR levels and neuromuscular function during postembryonic development. We propose experiments to define and elaborate upon this signaling system at the Drosophila NMJ. Given that these signaling molecules are highly evolutionarily conserved, we predict that our data will have direct relevance to the function of NF-kB during neural disease and injury in mammals. PUBLIC HEALTH RELEVANCE: In the nervous system, NF-kB signaling system has been implicated in the mechanisms of neurodegenerative disease, epilepsy, and the response to neuronal injury. Despite the importance of this evolutionarily conserved signaling system, very little is known about how NF- kB participates in these diverse processes. We propose experiments that will not only define how NF-kB is activated in the nervous system, but will also define an output for NF-kB signaling that may be directly relevant to the role of NF-kB during injury and disease.